BCP 38 is like herd immunity with immunization, and much like anti-vaccine folks, networks that don't follow it are knowingly choosing to infect people for any number of reasons. Despite your claim, it is
extremely easy to implement and has been a known best practice, with accompanying educational Web sites devoted to the topic[0], for many years. There are nearly zero reasons for your AS to transmit forged packets, and if your configuration allows it, you are
knowingly making the Internet a worse place with your laziness and transferring your laziness to other people like me that carry pagers. This isn't a surprise to any network administrator unless they've spent their entire career not reading RFCs.
I'm of the opinion that networks that allow customers to emit forged source addresses should be depeered until they take the literal hour to fix it. "But we have to update equipment when we get new blocks!" Boo hoo. Automate it or get off the Internet so I can stop spending my life dealing with your customer's amplified traffic.
If you run a non-transit/eyeball AS, you are in the absolute best position to stop these types of attacks from ever happening. The rest of the Internet, particularly your transit peers, can't really clean up after you on this one. Do us all a favor.
[0]: http://bcp38.info